Norton relays melting

[cbax]

On 2 furnaces both nortron i have found relays that were stuck closed and melted causing them to stay in the on state.  This cause the furance to heat one element till it over heats then repeats.

Anyone have a better solution for the relays they are using? 
Both furnaces use a HF105f-4  or a T9AP1D52-24

They are both rated 30 amp

You can see the result on 2 of the furnaces.  one i went to replace the relay only to find the other relay had done the same whil waiting for the part:

https://photos.app.goo.gl/SESgMh26yNerMvco6